1. Technical Field
The present disclosure relates to light guide plates and backlight modules and, particularly, to a light guide plate for direct-type backlight module and a direct-type backlight module.
2. Description of Related Art
Currently, because liquid crystal displays (LCDs) are thin, lightweight, long lasting, and consume little power, they are extensively used in a variety of electronic devices. However, liquid crystal displays are not self-luminescent, therefore, backlight modules are typically required. Generally, backlight modules can be categorized as either direct-type backlight modules or edge-type backlight modules. Because direct-type backlight modules can provide high illumination in comparison with edge-type backlight modules, direct-type backlight modules are more widely employed in numerous applications.
Direct-type backlight modules, according to the prior art usually include a point light source such as light emitting diode (LED), a reflective plate, and a light guide plate. The light guide plate has a bottom surface and a top surface opposite to the bottom surface. The point light source is located adjacent to the bottom surface. The reflective plate is located on the side of the bottom surface. The light radiated from the point light source enters the light guide plate and hit the top surface with different incident angles. The first part of the lights leave the light guide plate through a refraction of the top surface, and the second part of the light enter the light guide plate through a reflection of the top surface. The second part of the light will leave the light guide plate after refraction between the top surface and the reflective plate. However, an illumination of the light guide plate is not uniform because the illumination of a center part of the top surface opposite to the point light source is more extreme.
What is needed, therefore, is to provide a light guide plate that has improved uniformity of illumination and a direct-type backlight module using the same.